Exhaust-gas heat exchanges of this kind are described in EP 1 555 421 A2 and JP 2010/31671 A, according to which the Inner pipe has a perforation and the axial flow cross section can be closed by a valve, so that the exhaust-gas flow can be guided through the inner pipe and/or across the exhaust-gas heat exchanger in the outer pipe.
In DE 10 2010 039 281 A1 a similar waste heat recovery device is described with central throttle valve, by which the mass flow is regulated in the central passage line and in the bypass line.
JP 2008-101479 A likewise describes a device for heat exchange in an exhaust-gas flow, which is regulated by a central throttle valve. Cooling is done in the countercurrent method.